[xiph-commits] r13948 - trunk/theora/doc/spec

[giles at svn.xiph.org]

Author: giles
Date: 2007-10-09 17:01:57 -0700 (Tue, 09 Oct 2007)
New Revision: 13948

Modified:
   trunk/theora/doc/spec/spec.tex
Log:
Document the 3.2.0 granulepos scheme.


Modified: trunk/theora/doc/spec/spec.tex
===================================================================
--- trunk/theora/doc/spec/spec.tex	2007-10-09 23:44:59 UTC (rev 13947)
+++ trunk/theora/doc/spec/spec.tex	2007-10-10 00:01:57 UTC (rev 13948)
@@ -7746,6 +7746,15 @@
 by the Ogg format, but contains information necessary to efficiently 
 find the previous keyframe to continue decoding after a seek.
 
+Prior to bitstream version 3.2.1, data packets were marked by a 
+granulepos derived from the index of the frame being decoded,
+rather than the count. That is they marked the beginning of the
+display interval of a frame rather than the end. Such streams
+have the VREV field of the identification header set to `0' 
+instead of `1'. They can be interpreted according to the description
+above by adding 1 to the more signification field of the split 
+granulepos when VREV is less than 1.
+
 \section{Multiplexed stream mapping}
 
 Applications supporting Ogg Theora I must support Theora bitstreams